Field-scale variability of weediness on arable land

Weed mapping was conducted on 2 fields in Central Bohemia to characterize the spatial structure and temporal stability of weed populations over four years (1999-2002). A number of plants for each species and the total weed coverage were investigated on the grid points. To determine the weed infestation variability, and the Patchiness-Index was calculated. Use of Surfer-software, and weed maps were created. For single weed species occurrence the correlation between 1999 and 2000 was calculated. The results document heterogeneous occurrences of weeds, especially Cirsium arvense (PI = 9.09-15.86), Tripleurospermum maritimum (PI = 11.01-217.30) and Galium aparine (PI = 4.61-7.70), whereas Viola arvensis and Stellaria media were distributed more homogeneously. Weed grasses occurred in all years slightly. G. aparine is characterized by relatively high spatial stability.